In the following description, the term “yarn” is intended to include the threads, tapes, profile tapes, fibrillated tapes and slit-film bands of various linear mass density, diameter, width and thickness. The term ‘yarn’ is also used to describe yarn with multiple threads or ends that a single winder might receive. The term “bobbin” is intended to include any metallic or non-metallic tubes on which the yarn is wound to form a suitable package.
Automatic turret type winders are used in production or take-up process of continuously advancing yarn, for example, in yarn extrusion machines or in rewinding process for making plurality of small size yarn packages from a large yarn package. In general, the turret type automatic winders are positioned side by side in the horizontal direction and stack one above the other in vertical direction. The number of winding positions is exemplary both in horizontal row and vertical row.
The yarn transfer operation is important in the automatic yarn winding operation. If the yarn is not transferred in the first attempt, the continuously advancing yarn gets wasted until it is rethreaded. Worse still, the continuously advancing yarn, if not controlled properly in case it fails to transfer onto the empty bobbin, may interfere with the other yarn winders on the same machine and cause the entire machinery to stop which results in a huge amount of wastage, machine downtime and economic loss. In the worst situations, some parts of the machinery may get damaged.
In automatic turret type winders, a continuously advancing yarn is generally wound on an initially empty bobbin to form a suitable yarn package. When the pre-determined package size (length/diameter/time) is achieved on a bobbin installed on one of the bobbin holders, generally known as a spindle, the continuously advancing yarn is transferred to an empty bobbin installed on another spindle to make a new yarn package. The yarn transfer is carried out by an automatic transfer device and without interrupting the winding operation.
Some of the known devices for transferring the yarn to the grasping device, such as the one disclosed in EP 03725171, involve complex mechanisms. The yarn transfer is achieved by a movement of the entire swivel box that houses the traversing mechanism. This type of movement, which involves the axial displacement of a large mass, requires a complex and expensive device for its execution. Another device, disclosed in the U.S. Pat. No. 8,267,342, uses a mechanical system with special traverse guide mechanism of introducing advancing yarn into a grasping device during the bobbin changeover operation in automatic winder. However, there are a few drawbacks in this system: precision required in the setting of links and limitation in separating yarn from traverse guide and precise, consistency required in re-insertion of yarn back into traverse guide.
One key drawback of prior art systems where the winding operation needs stopping of traverse device during the changeover process is that it reduces the speed and efficiency of the winding operation. The conventional systems that allow yarn transfer without the stoppage of the winding operation are bulky and complex.
There is therefore a need to provide a simple mechanism of achieving the yarn transfer to the catchment area of an empty bobbin followed by returning the yarn to the winding area without stopping the traverse device.